Platen-carriage shift and rebound lock for typewriters



Nov. 16 1926; 1,606,998

O. A. HOKANSON PLATEN CARRIAGE SHIFT AND REBOUND LOCK FOR TYPEWRITERS Filed Jan. 31. 1924 R a 5%, Q

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platen carriage in its lowermost position 7 there is a tendency of the carriage to rebound when theshift key is released and the carriage drops to its downward limit of movement as determined by the stops 44 To overcome this tendency an arm 45 is mounted on the pivot'2'1 which carries the shift frame and is adjustably connected to the shift frame by a screw and slot connect-ion d6. A lever 47 is mounted at the left-hand side ofthe machineon the pivotal support 48 for the sub-levers and is pro- 0 l G l i vided with a contact face 49 for engaginga pin 50 on the lower end of the arm 45. A depression 51. is provided at the'rear end of the contact face 49 forreceiving the pin 50.

IVhen'the pin 50 is seated in the depression 51 theashi'ft frame 20 is locked againstfmove pivot pin 5& which engages an elongated slot 55 in'the link '52.- r

A slight amount of lost motion is pro-. vided at 56 between the arm 2% of the shift lever 22 and'the contact abutment-for the shift frame 20. WVhen a shift key is de- 7 pressed the pin l1 willimpart a slight movement to the cam 39 and consequently to the extension 53 before the arm 124;"come'sIin contact with the shift frame 20. fThis pre liminary movement will rotate the lever 47 1 in a clockwise direction a sufficient amount to free the pin 50 fromthe depression 51 and permit movement of the shift name when the arm 24 engages the shift frame,

During the shifting movement of the platen the pin 50 will travel along the contact face 49, thus holding the lever 47 in its depressed position. Whenthe shift key is released the arm will move backwardly along'the contact face'4 c9 until the pin registers with the depression '51 at which time the coil spring 57 will draw the link 52 forwardly and snap the lever 47 upwardly= to cause the depression 51=to engage the pin '50 and thus lock the platen carriageagainst rebound, movement. It will thus-be seen T that the mechanism'provides alock for the carriage when it reaches its lower position i and prevents any rebound which mightre- V sult in blurring of. the letters. Meansis also provided 'for'locking' the 'platen' in its upper position by keyat either side of the keyboard and the carriage may Berra leased by pressing the shift key at either side ofthe keyboard irrespective of the side at which "the shift {lock key has been erated.

I claim r I r l. Thecombination with a shiftable element for changing from one case to another,

of a key lever for shifting said element, a locking lever for retaining said element against movement, a' pivoted arm, a link connecting said locking lever and arm and having a pin and slot connection with said arm, a cam connected with said arm, andia contact member on said case shift lever for moving said arm. y ,7

i 2. In a typewriter, a main frame, a platen carriagemounted to travel on said frame, a vertically shiftable platen on said platen carriage, a shift frame mounted on said main frame, a shiftrail carried by said'shift frame, a roller connected:.with said platen for travelingon said shift rail, a detent connected with'said platen for holding said roller against movement away from said rail, a counterbalance spring connected with said shift frame, an arm adjustably connected with said shift frame and having a pin thereon, a locking leverhaving an elongated contact face for engaging said pin and having a depression at one end of said face for locking said pin to hold said shift frame against upward movement, a pair of case as. j

shift key levers, a shaft extending trans- I versely of said frame and having an arm secured thereto, a link pivotally connected with said lockinglever andhaving a pin and slot connection with said arm, aipair of cam levers adjustably mounted on said transverse shaft, and means on each of: saidlcase shift keylevers for, engaging oneof said cam levers to rock said shaftland release said shift lock connected with each of said lelOcking lever from said pin at the beginning vers and having a locking key thereon, a

transverse shaft, means on said shaft for releaslng sald shift locks, and means for actuatingsaid shaft when either of said shift 5.fIn comb-ination, a pair of shift levers 7 provided with alock key, a ,springi for re- 7 taining. said shift lock. in retracted position, a transverse shaft having a pair of contact devices thereon for engaging-said shift locks to release the same, and a pairofcam members on id-shaft .a r ranged to cooperate with said shift levers to 1rotate.saidnshaft upon operation of either of saidshift levers. 6. The combination with a shiftable element for. changing from one case to another, of a lock for preventing rebound of said element, a shaft for releasmg said looks, a pair ,each having 'a shift lock"mountedlthereon 7 of case shift levers, shift locks connected ing said shift locks, and means for operating said shaft when either of said case shift levers is depressed. v I

7. The combination With a vertically shiftable platen, of a look for preventing rebound of said platen, a pair of case shiftv 10 levers, shift locks for said levers, detents for said shift locks, a common device operated by either of said case shift levers When depressed, means operated by said device for releasing said rebound lock, and means operated'by said device'for. releasing either of said case shift locks. v p

In testimony whereof I have signed my name tothis specification on this 29th day of January, A. D. 1924.

OTTO A. HOKANSON. 

